Honeycomb sandwich panels (e.g., a honeycomb core structure sandwiched between two layers of material, or skins) are often used in the construction of aircraft, because they have high strength to weight ratios. Depending on the specific location and application of a honeycomb structure in an aircraft, two or more honeycomb sections may be required and may be joined or bonded together to define a larger honeycomb structure. In some applications, such as joining panels in constructing overhead storage bins for an aircraft (which can also be referred to as a bin bucket or stow bin), a curved sandwich panel is joined to a straight sandwich panel.
In a conventional method of joining a flat panel to a curved panel, a joint is created by machining interlocking “fingers” in the two panels to be joined, and adhering the panels together. A first panel 100 (FIG. 1A) has a honeycomb core 104 sandwiched between a first skin layer 102 and a second skin layer 103. Portions of panel 100 are machined to remove areas of skin layer 102 and some or all of core 104, thereby forming a plurality of fingers 105 and cut-outs, or recesses 106 and resulting in a staggered edge 107. In some techniques, substantially all of core 104 is removed from areas of each recess 106, such as shown in FIG. 1B. A manual scraping step is often performed to remove remnants of core 104 from portions 108 of each recess 106. Such scraping can result in areas of the second skin layer 103 having no core 104 attached, but can be difficult and time-consuming to perform.
A second panel 120 (FIG. 2) also has a honeycomb core 122 sandwiched between a first skin layer 124 and a second skin layer 126. Second panel 120 is also machined to form a staggered edge 127 having alternating fingers 128 and recesses 130. Each finger 128 of panel 120 is sized to correspond to and fit within a respective recess 106 of panel 100, resulting in a staggered joint 132 (FIG. 3). Likewise, each finger 105 of panel 100 is sized to correspond to and fit within a respective recess 130 of panel 120. FIG. 4 shows a schematic view of joint 132. Adhesive 134 is applied along staggered edge 107 and/or staggered edge 127, and the respective fingers and recesses of the two panels are interlocked with one another to secure the joint together.
Conventional manufacturing techniques may result in inconsistent production results, rippling, and/or curling inwards of one or both of the panels. Such curling or rippling often results in buckling and/or wavy internal joints in the finished product (e.g., aircraft storage bin). Such flawed joints may be visible to airline passengers, and thus manufacturers often must scrap or dispose of such defective parts, wasting time and money, and/or attempt to mitigate the curling, thereby increasing production costs and time. Mitigation of the curling is often not entirely effective to improve the visual quality of the resulting parts and also increases production times. Thus, there remains a need for an improved method of joining honeycomb sandwich panels.